Caviar Black
Used by 2 peopleamazon.com ↗

“My hardware is an Athlon triple core CPU (2.9 Ghz) with 3Gb DDR2 RAM; GeForce 9600 GT videocard; X-FI Xtreme Music sound card; 6 HDDs, each 1Tb Hitachi (for backups and file storage), two Samsung and one WD Caviar Black drives for OS, swap and software.”
Boris Vorontsov Interview, Game developer, modder · via Uses This 
“The first thing I did when I got it was to put 2x 1 Gb Western Digital Caviar Black drives to make a stripped RAID, which in theory makes saving files almost 2x fast when compared to using one drive.”
Kevin Meredith Interview, Photographer, teacher · via Uses This